Chiral aggregation hierarchy in high-pressure resolved 2-butanol and 2,3-butanediol

Abstract

High-pressure isochoric freezing of (±)-2-butanol and (±)-2,3-butanediol yields enantiomorphic conglomerates, both of the P212121 orthorhombic space-group, with isostructural OH⋯O bonding patterns. Although the volume was compressed by two orders of magnitude more than was expected from the Wallach's rule, the crystallization of the racemates has not been enforced. The single crystals have been crystallized in situ in a diamond-anvil cell, their structures determined by X-ray diffraction and their compressibility measured in a piston-cylinder press. The chiral molecules OH⋯O hydrogen bond into helices of 2-butanol and chiral sheets of 2,3-butanediol, which in turn favour enantiomorphic crystallization, irrespective of the volume changes.